The potential health benefits of marine oils in vascular disease are being intensively investigated, including their effects on platelets, endothelium, and lipoproteins (LP). Although there is a great interest in atherogenic events occurring during post-prandial lipemia, however, no studies have yet defined the post-prandial interactions of these elements in humans. The object of the proposed research will be to utilize state- of-the-art GC/MS methods to 1) define the alterations of platelet and vascular eicosanoid synthesis during lipoprotein processing in vivo; 2) determine how such effects are changed by the ingestion of marine oils; and 3) assess the effects of N-3 fatty acids (FA) on the generation of oxygenated sterols and fatty acids in bile and the delivery of such products to the gastrointestinal tract for incorporation into nascent chylomicrons. Both physiological and pharmacological approaches will be made to define several important aspects of platelet/vascular/lipoprotein interactions in humans, and how they are influenced by marine oils. By doing so, the proposed project directly addresses in vivo several important hypothesis underlying current theories of human atherogenesis, and thereby will help to define more clearly the potential health benefits of marine oils in Western societies.